Removing inhibitors from



Patented Sept. 25, 1951 REMOVING INHIBITORS FROM DRYING OILS Henry A. Vogel, Milwaukee, Wis., assignor to Pittsburgh Plate Glass Company, Allegheny County, Pa., a corporation of Pennsylvania No Drawing. Application August 19, 1948, Serial No. 45,210

9 Claims. 1

The present invention relates to a method of treating glyceride oil, of the drying or semidrying class and it has particular relation to a method of treating drying or semi-drying oils which include high concentrations of natural inhibitors of air drying.

One object of the invention is to provide from the glyceride oil containing fatty acid radicals of a highly unsaturated nature, said oil containing inhibitors, a composition which will more readily air dry than the untreated oil.

- A second object of the invention is to provide a process of treating a glyceride oil containing inhibitors of drying in order to eliminate them or reduce the proportion thereof.

A third object of the invention is to provide a process of treating glyceride oils containing tocopherol or other inhibitors in order to selectively oxidize them to a non-inhibitory state or form, without substantial production of peroxides of the fatty acid radicals contained in the glyceride molecules or the breaking apart of the tri-glyceride molecules to liberate free fatty acids.

- A fourth object of the'invention is to provide a process of eliminating inhibitors or substantially reducing the content of inhibitors in'drying glyceride oils or glyceride oils containing drying components, which is simple in its character and inexpensive to operate.

A fifth object of the invention is to provide a process of treating oils in which the components of higher iodine value, along with the inhibitor components, have been concentrated by solvent fractionation, whereby to reduce, or eliminate the inhibitor content. 7

' A sixth object of the invention is to provide a process of treating glyceride oils to improve the color thereof by selective oxidation of carotenoids and similar pigments.

A seventh object of the invention is to provide a process of treating glyceride oils containing inhibitors of drying, whereby to obtain a product which dries and bodies faster and is more uniform in behavior than untreated oils.

An eighth object of the invention is to provide an oily suitable for use in the manufacture of soaps and similar purposes, which does not re-.

quire drastic decolorization treatment and which when manufactured into soap or similar materials does not undergo discoloration upon aging. It is to be understood that the order of the objects of the invention as above listed has no relation to the order of the importance attached to the various objects.

These and other objects of the invention will be apparent from consideration of the following specification and the appended claims.

It is a well-known fact that various of the natural glyceride oils contain small amounts of inhibiting chemical compounds whose presence greatly adds to the stability of the oil. These natural anti-oxidants are desirable when an oil is to be processed into an edible product, since such product is normally desired to :be of greatest possible stability and highly resistive to oxidational changes. However, when an oil is to be processed into a drying composition, for example a drying oil for use in paints or varnishes, where its ability to react with oxygen or otherwise to undergo chemical change to form a hard and durable film, is of prime importance, the presence of significant amounts of anti-oxidants is usually undesirable.

The action of these anti-oxidants in slowing up the drying rate of drying oils, even linseed oil can easily be demonstrated. In a specific test, linseed oil which is one of the best allaround drying oils, was compounded with of its own weight of titanium pigment, thinned with naphtha and incorporated with conventional driers. The specific drier preferably comprised 0.24% lead, 06% cobalt and 02% manganese on the basis of the oil weight. The oil employed contained 07% of inhibitol, probably tocopherol or its equivalent. One of these samples was employed as a control without addition of inhibitol. To a second sample, .l% of tocopherol was added. To a third sample, .2% of tocopherol was added. These samples after compounding with pigments, naphtha, and driers, as-above described were then spread as uniform films upon plates of glass and were subjected to drying and the drying times of each sample noted. The result of the tests are tabulated as follows:

Drying Inhibitor Time Content,

Linseed oil 5.5 hrs. .07 Linseed oil plus 0.1%

added anti-oxidant 11.0 hrs. .17 Linseed oil plus 0.2%

added anti-oxidant 18.0 hrs. .27

It has, heretofore, been proposed to extract with partially immiscible solvents, e. g. furfural, glyceride oil and notably glyceride oils containing at least a portion of glycerides of unsaturated fatty acids which have drying characteristics, in order to obtain a concentrate of the more unsaturated components of the 011. Such processes are disclosed in Freeman Patent 2,200,391 and also in a patent to Ruthruff et al. 2,355,605. lhe fractions so obtained are of substantially higher degree of unsaturation than the original oil as indicated by their iodine number value, but at the some time that the more unsaturated glycerides are fractioned off in the polar solvent, there is also obtained a corresponding fractionation or separation in the more unsaturated oil, of inhibitors that tend to retard drying. In Patent 2,355,605 it is proposed to obviate this concentration of the inhibitors in the extracted oil by further subjecting the extract solution of oil in furfural to extraction with naphtha which-extracts out the glyceride oils from the furfural phase. Supposedly the inhibitors, free fatty acids and the like remain in solution in the furfural phase. However, in actual practice, it is found that such inhibitors as tocopherol are also strongly extracted out of the furfural phase by the naphtha, so that-the resultant oil of higher iodine value may, in certain cases, contain sufiicient inhibitor greatly to retard the drying rate. This is particularly true in the case of inhibitor rich oils such as soybean oil.

The present invention contemplates the provision of a simple and convenient process whereby the inhibitor content and notably the tocopherol content of inhibitor rich oils such as soybean oil and particularly of extracts of oils such as are obtained by the-process disclosed in the foregoing patents can be reduced or substantially eliminated.

- Essentially, the invention is based upon the discovery that inhibitols such as tocophe-rol in glyceride oils can be selectively removed or deactivated by subjecting the oil to air oxidation in the presence of catalysts of oxidation such as the conventional cobalt, lead, manganese, or the like metallic driers, normally employed in paints, varnishes and similar coating compositions in order to speed up drying or hardening of the oil, without appreciably changing the iodine value, body, acid value, peroxide value, or other properties of the oil.

a It is to be recognized that it has. heretofore been proposed to body drying oils such as linseed oil byan intensive and prolonged air blowing operation, that is non-selective in its character and produces substantial reduction of iodine value, in-

glyceride oil with .air results in increase of theperoxide value of the oil, for example, to a range of 30 to 300 after the bodying operation. Selective oxidation of the inhibitors in the oil, in accordance With the present invention, does not result in an appreciable increase of the peroxide value. The peroxide value after treatment in accordance with the present invention usually is below 5 and never above points. The essential feature of the invention resides in the reduction of the inhibitor content which preferably is determined by the conventional Emmerie-Engel method, The present invention contemplatesthe reduction of the inhibitor content as determined by this method by at least 50% and preferably lower, for example by 98%. In practically all cases. the inhibitor content will be reduced to .1 or below of the oil content.

Oils susceptible of treatment In the practice of the invention substantially any oil comprising triglycerides of fatty acids and containing undesirable e. g. over 0.1% inhibitors may be treated. Linseed oil may be treated but in most instances the inhibitor content of this oil is so low inherently as not to require treatment to eliminate inhibitors. However, in event that the oil contains objectionable amounts of such inhibitors, it may be successfully treated. Oils which are to be employed as soap stocks or for other similar uses may also be'treated. Such oils may, for example, comprise soybean oil, cottonseed oil, corn oil or others containing inhibitor such as tocopherol. These oils, when subjected to the conventional saponificaton reactions, sometimes result in soaps which upon aging undergo discoloration apparently by reason of oxidation of the inhibitor content thereof. For this reason, it has. heretofore, been proposed to subject soap stocksv to radical decolorization treatments. It is now found that the stocks can be successfully treated by the simple and convenient technique of the present invention to attain the same results.

The invention is particularly applicable to drying oils and especially those drying oils: which are rich in inhibitor. Soybean oil constitutes an example of such material. soybean extract oils which have been extracted out of whole soya oil by fractionation with polar solvents such'asv furfural as disclosed in. Freeman Patent No. 2,200,391 are especially rich in inhibitors. The inhibitors are concentrated in the furfural extract phase along with high iodine value triglycerides.

The catalysts In the practice of the invention, the addition of small amounts of catalysts of oxidation and,

notably catalysts such as are conventionally employed as driersin paints and varnishesis im}. portant. These catalysts include the various salts of heavy metals such as cobalt, nickel, chromium, manganese, lead and the like that have at least a slight solubility in the oil. example, be the oleates, linoleates, naphthenates, resinates or the like of: the foregoing metals. The manufacture of such driers is well understood by those skilled in the art. The amount of the drier as stated, is small and usually will be Within a percentage of .0001 to .001. ferred range is .0002 to .0006. These percentages are calculated as active metal based upon the total amount of oil which is treated.

' The temperature of operationv The addition of Oxygen Air constitutes the usual oxidizing agent, but

it is to be understood that oxygen gas could also be employed by appropriate adjustment of the amount and the rate of addition. The air (or oxygen) is more effective if it is as thoroughly The salts may, for- The pre-.

distributed in the oil which is undergoing treatment as is reasonably possible. .Various types of agitation may be employed. For example the air may be whipped or stirred relatively uniformly in tiny bubbles in the oil by means of conventional agitators or turbo-agitators. It is also contemplated to break up the air or oxygen as it is supplied to the oil by bubbling it into the oil through appropriate distributor heads provided with minute openings.

In most instances, thetotal amount of air (assuming air is employed as the oxidizing agent) will not exceed 2.5 cubic feet of air per gallon of 'oil. The range in proportions will be approximately .2 to 2.5 cubic feet per gallon of oil treated. The preferred range is .2 to 1 cubic foot of air per gallon of oil. Considerable variation in the rate of addition of air (or oxygen) can be tolerated but usually the rate will be within the range of .005 to .02 of air or .001 to .004 of oxygen expressed in terms of cubic foot per minute per gallon of oil treated; It will be understood that if oxygen is employed, the necessary reduction in volume to compensate for theincreased con-. centration of the active agent will be made.

The time of treatment The time of aeration is susceptible of substantial variation but in most instances the time will be within a range of to 90 minutes. The optimum time is approximately 45 to-90 minutes. It will be appreciated that excessively protracted air blowing will result in increases in the viscosity of the oil, increase of peroxide values, increase of acid value and other changes which may be objectionable. Treatment may be stopped when the peroxide value begins to rise objectionably.

I The completion of the treatment of the oil can easily be determined by conventional tests for inhibitors, for example, the above mentioned Emmerie- Engel test. As previously stated, the overi all inhibitor content will be reduced by at least and maybe as low as 98%. The content will usually be reduced beolw .1%. In the normal treatment of the oil, 90% of the inhibitors can be destroyed along with 75 to 90% of the carotenoid pigments without appreciably efiecting the oil in other respects. When the inhibitor content is sufficiently low, air blowing should be stopped before reviously mentioned objectionable changes become pronounced.

After the inhibitor content of the oil has been adequately reduced, the reaction may be stopped without further treatment. However, it is also contemplated to blow the oil for a short time with an inert gas such as nitrogen, carbon dioxide or steam in order to remove traces of decomposition products which may give the oil a so-called blown oil odor. This latter treatment is also beneficial in that it tends to reduce peroxide value of the oil.

The following constitute specific examples illustrating the application of the principles of the invention. These examples are by way of illustration.

Example 1 500 gallons of soya extract oil whose iodine value was 152.0 and whose tocopherol concentration was 0.23% was heated to 265 F. and treated with 5 cubic feet per minute of air under agitation in the presence of 65 grams of a 6% cobalt naphthenate in naphtha solution. The cobalt concentration was approximately .0002% (based upon the oil). The treatment was continued for 6 one hour, at which point the air was stopped and the oil was steamed 15 minutes at 260-265 F. At the end of this time the oil was cooled.

The following table indicates the difference in the oil:

Before After Treatment Treatment Iodine valueuh 152.0 151.2

Inhibitol, 1- 0.23 .021 Gardner Co1or 9.5 9.0 Peroxide Value 0.6 1.2 Set-Time, hrs.* 21.0 6.5

* Set Time is determined by grinding the oil with a single pigment, adding naphtha thinner and driers to it and applying the resultant onepigment paint with a doctor blade onto a glass panel for drying. The drier concentration used is generally 0.23% active lead and 045% active manganese.

Example 2 An example of the use of the oil, of Example 1 in a house-paint formulation may be presented.

Grind:

Pounds 35% leaded zinc oxide 406 T102 pigment -1 82 Rutile pigment 82 Powdered asbestos 183 Mica powdered 23' Soya extract oil treated for inhibitol destruction 244 Soya extract oil treated for inhibitol destruction and heat-bodied to a Gardner Holdt Y viscosity 122 Naphtha 46 These ingredients were ground together and thinned as follows: 1

6.0 lbs. of 24% liquid lead naphthenate naphtha solution 1.8 lbs. of 6% liquid manganese naphthenate naphtha solution 141 lbs. naphtha Specifications Lbs/gal 13.37 Lbs. oil/gal 3.66 Pigment volume concentration 31.5% Consistency sec.; 4 Ford Cup Drier 0.4% Pb on oil;

0.03% Mn on oil The basic formulation presented was varied in that the vehicle consisted of (a) crude and Y-bodied linseed oil; and (b) limpid and Y-bodied soya extract not treated for inhibitol destruction. Each of the three oils were also formulated with the same paint with the vehicle containing equal weights of the Y-bodied and unbodied oil. The drying of these paints consistently showed the aerated oil to be better drying than the unaerated and the virtual equal of the formulation containing crude and Y-bodied linseed oil.

Example 3 A sample of the aerated oil was further airblown to a viscosity of 4 poises. It was found that this blowing was accomplished in four hours, which time added to the aeration time initially used is a total time of 5 hours.

Oils of the same viscosity were prepared from crude linseed oil and refined linseed oil by direct air-blowing at equivalent temperatures. These oils required 10.5 and 9.0 hours, respectively, to attain this viscosity. The drying the blown oil was compared and the soya extract oil was found to dry as rapidly and was more thoroughly through-dried in four hours than were the linseed oils, which exhibited surface drying and. were soft or even liquid under the top skin when applied at equal wet film thickness. The driers used were 0.23% lead and 045%. manganese as naphthenates.

The oil after treatment could be incorporated with pigments, thinners and the like to make paints and varnishes.

Cottonseed oil and others could be air blown as described in Example 1 to provide good soap stocks.

Drying oils treated by the technique herein disclosed, dry far faster than. untreated oil. The acid value, iodine value, peroxide value and the viscosity are not appreciably changed. Color is usually improved by oxidation of carotenoid pigments and the like. Discoloration by oxidation of such agents as tocopherol is eliminated or minimized.

I claim: V

1. In a process of treating a drying glyceride oil containing at least .1% of natural drying inhibitors, thesteps which comprise incorporating with the oil an organic carboxylic acid salt soluble therein, which salt is of heavy metal that forms fatty acid compounds that accelerate air drying of the oil, the active metal being-present in an amount of .0001 to .001 percent, then bubbling gas comprising oxygen through the oilat a rate of .001 to .004 cubic feet of oxygen per minute per gallon of oil treated, the temperature of treatment-being'within the range of 230 to 280 F., treatment continuing over a period of 10 to 90 minutes whereby to reduce the inhibitor content by 50 to 98%.

2. A process as defined in claim 1 in which the oil treated'is soybean oil enriched in inhibitors of air drying by selective extraction of the more unsaturated glycerides of the soybean oil and the inhibitors of drying by solvent fractionation.

3. A process as defined in claim 1 in which the catalyst is a naphthenic acid salt of the heavy metal.

4. A process as defined in claim 1 in which the catalyst is the oleic acid salt of the heavy-metal conventional in siccatives in drying oils.

5. A process as defined in claim 1 in which the catalyst is a carboxylic acid salt of a metal of a class consisting of cobalt, lead, manganese, chromium and nickel.

6. A process as defined in claim 1 in which the salt is cobalt naphthenate.

7. A process as defined in claim 1 in which the salt is cobalt oleate.

8. A process as defined in claim 1 in which the oil treated is soybean oil extracted from soybean oil with furfural and the oil is treated with a total of .2 to 2.5 cubic feet of air per gallon of oil.

9. A process as defined in claim 1 in which the oil is treated with an inert gaseous medium after the blowing with air.

HENRY A. VOGEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,337,339 Booge Apr. 20, 1920 1,438,222 Craven Dec. 12, 1922 2,023,768 Ott Dec. 10, 1935 2,079,763 De Groote May 11, 1937 2,334,391 De Groote Nov. 16, 1943 2,388,122 Colbeth Oct. 30, 1945, 2,403,408 Stamberger July- 2, 1946 OTHER REFERENCES Industrial Oil and Fat Products," 1945 ed., pages 385, 386, 389, by A. c. Bailey, Interscience Publishers, Inc., N. Y. 

1. IN A PROCESS OF TREATING A DRYING GLYCERIDE OIL CONTAINING AT LEAST .1% OF NATURAL DRYING INHIBITORS, THE STEPS WHICH COMPRISE INCORPORATING WITH THE OIL AN ORGANIC CARBOXYLIC ACID SALT SOLUBLE THEREIN, WHICH SALT IS OF HEAVY METAL THAT FORMS FATTY ACID COMPOUNDS THAT ACCELERATE AIR DRYING OF THE OIL, THE ACTIVE METAL BEING PRESENT IN AN AMOUNT OF .0001 TO .001 PERCENT, THEN BUBBLING GAS COMPRISING OXYGEN THROUGH THE OIL AT A RATE OF .001 TO .004 CUBIC FEET OF OXYGEN PER MINUTE PER GALLON OF OIL TREATED, THE TEMPERATURE OF TREATMENT BEING WITHIN THE RANGE OF 230 TO 280* F., TREATMENT CONTINUING OVER A PERIOD OF 10 TO 90 MINUTES WHEREBY TO REDUCE THE INHIBITOR CONTENT BY 50 TO 98%. 